Fibrous histiocytoma simulating congenital fibromatosis: a light-, electron microscopic and tissue culture study.

The unusual occurrence of a fibrous histiocytoma of subcutaneous soft tissues, bones, and viscera is described in a newborn infant. The clinical and radiologic picture simulated a congenital fibromatosis, but histologic, electronmicroscopic and tissue culture studies indicated a malignant tumor with a bimodal cell population resembling immature fibroblasts and histiocytes. Although less mature and more uniform, it essentially parallels the findings in the adult malignant fibrous histiocytomas.